Pulse combustion technology has been widely utilized in heating units such as water heaters using natural gas or other gaseous fuels as well as liquid fuels. In pulse combustion burners of the Helmholtz type, a combustion chamber of a given size is connected to an exhaust or tailpipe of given length having a cross section somewhat less than that of the combustion chamber. An oscillating or pulsed flow of gasses through the burner is maintained by explosive combustion cycles in the chamber which by thermal expansion of the gaseous combustion products drives such products from the chamber and out of the exhaust pipe. Pulse combustion burners are generally characterized by high overall efficiency and high heat transfer characteristics. The high heat transfer properties of such burners are generally attributed to relatively high degrees of turburlence in the flow of combustion products which results from the high velocities and cyclic flow reversal of these combustion gases.
In order for the pulse combustion process to be self-sustaining, the burner is designed to operate in a resonant manner. The design parameters for a pulse combustion burner are established by the Hemholtz equation for a known or desired frequency of operation. The tailpipe length and geometry, as well as the combustion chamber geometry and fuel feed rates, cooperate to provide a resonant pulse combustion burner.
Typical examples of pulse combustion burners known heretofore are shown in U.S. Pat. No. 3,190,340 issued to Fritsch, U.S. Pat. No. 3,194,295 issued to Marchal et al., U.S. Pat. No. 3,192,986 issued to Haag, and U.S. Pat. No. 3,674,409 issued to Desty et al. Examples of deep fat fryers known heretofore are shown in U.S. Pat. Nos. 4,397,299 issued to Taylor et al., 3,760,793 issued to Anetsberger et al., 3,712,289 issued to Reid, Jr. et al. and 2,912,975 issued to Del Francia.
While pulse combustion processes have been known since the early 1900's, heaters utilizing these principals require large areas of space and can exhibit excessive noise levels as well as low efficiency levels. These drawbacks have heretofore rendered pulse combustion burners undersirable for utilization in heating units such as deep fat fryers which are used, for example, in fast food stores, restaurants and other commercial establishments.
Though the preferred embodiment of the invention is hereinafter described with particularity to a deep fat fryer, such description is for exemplary purposes only, and should not be interpreted as limiting in any sense in that many of the concepts disclosed herein have applications and alternative embodiments in pulse combustion burners in general.